//! 扩展的认证策略模块
//! 提供多种认证策略实现

use crate::auth::{AuthPolicy, AuthContext, AuthRequest, AuthResult, AuthError};
use async_trait::async_trait;

/// API Key 认证策略
pub struct ApiKeyAuthPolicy {
    api_keys: std::collections::HashMap<String, String>, // key_id -> api_key
    header_name: String,
}

impl ApiKeyAuthPolicy {
    pub fn new() -> Self {
        Self {
            api_keys: std::collections::HashMap::new(),
            header_name: "X-API-Key".to_string(),
        }
    }

    pub fn with_header(mut self, header: &str) -> Self {
        self.header_name = header.to_string();
        self
    }

    pub fn add_key(mut self, key_id: &str, api_key: &str) -> Self {
        self.api_keys.insert(key_id.to_string(), api_key.to_string());
        self
    }

    pub fn add_keys(mut self, keys: std::collections::HashMap<String, String>) -> Self {
        self.api_keys.extend(keys);
        self
    }
}

impl Default for ApiKeyAuthPolicy {
    fn default() -> Self {
        Self::new()
    }
}

impl AuthPolicy for ApiKeyAuthPolicy {
    fn authenticate(&self, request: &AuthRequest) -> AuthResult<AuthContext> {
        let api_key = request.headers.get(&self.header_name)
            .ok_or_else(|| AuthError::InvalidToken(format!("Missing {} header", self.header_name)))?;

        // 查找对应的key_id
        let key_id = self.api_keys.iter()
            .find(|(_, key)| *key == api_key)
            .map(|(id, _)| id.clone())
            .ok_or_else(|| AuthError::InvalidToken("Invalid API key".to_string()))?;

        let username = format!("api_user_{}", key_id);
        let mut context = AuthContext::new(key_id);
        context.username = Some(username);
        context.roles = vec!["api_user".to_string()];
        context.permissions = vec!["api.access".to_string()];

        Ok(context)
    }

    fn check_permission(&self, context: &AuthContext, required_policy: &str) -> AuthResult<bool> {
        if required_policy.is_empty() {
            return Ok(true);
        }

        if required_policy.starts_with("permission:") {
            let permission = &required_policy[11..];
            Ok(context.has_permission(permission))
        } else if required_policy.starts_with("role:") {
            let role = &required_policy[5..];
            Ok(context.has_role(role))
        } else {
            Ok(true)
        }
    }
}

/// OAuth2 认证策略
pub struct OAuth2AuthPolicy {
    _token_introspection_url: String,
    _client_id: String,
    _client_secret: String,
    required_scopes: Vec<String>,
}

impl OAuth2AuthPolicy {
    pub fn new(
        token_introspection_url: &str,
        client_id: &str,
        client_secret: &str,
    ) -> Self {
        Self {
            _token_introspection_url: token_introspection_url.to_string(),
            _client_id: client_id.to_string(),
            _client_secret: client_secret.to_string(),
            required_scopes: Vec::new(),
        }
    }

    pub fn with_required_scopes(mut self, scopes: Vec<&str>) -> Self {
        self.required_scopes = scopes.iter().map(|s| s.to_string()).collect();
        self
    }
}

impl AuthPolicy for OAuth2AuthPolicy {
    fn authenticate(&self, request: &AuthRequest) -> AuthResult<AuthContext> {
        let _token = request.get_bearer_token()
            .ok_or_else(|| AuthError::InvalidToken("No bearer token found".to_string()))?;

        // 这里应该调用OAuth2的token introspection端点
        // 为了简化，我们模拟一个成功的响应
        // 实际实现需要使用reqwest或类似的HTTP客户端
        
        // 模拟响应
        let user_id = "oauth_user_123".to_string();
        let mut context = AuthContext::new(user_id);
        context.username = Some("oauth_user".to_string());
        context.roles = vec!["oauth_user".to_string()];
        context.permissions = vec!["oauth.access".to_string()];

        Ok(context)
    }

    fn check_permission(&self, context: &AuthContext, required_policy: &str) -> AuthResult<bool> {
        if required_policy.is_empty() {
            return Ok(true);
        }

        // 检查OAuth scopes
        if required_policy.starts_with("scope:") {
            let required_scope = &required_policy[6..];
            Ok(context.has_permission(required_scope))
        } else {
            Ok(true)
        }
    }
}

/// LDAP 认证策略
pub struct LdapAuthPolicy {
    _ldap_url: String,
    _base_dn: String,
    _bind_dn: String,
    _bind_password: String,
    _user_filter: String,
}

impl LdapAuthPolicy {
    pub fn new(
        ldap_url: &str,
        base_dn: &str,
        bind_dn: &str,
        bind_password: &str,
    ) -> Self {
        Self {
            _ldap_url: ldap_url.to_string(),
            _base_dn: base_dn.to_string(),
            _bind_dn: bind_dn.to_string(),
            _bind_password: bind_password.to_string(),
            _user_filter: "(uid={username})".to_string(),
        }
    }

    pub fn with_user_filter(mut self, filter: &str) -> Self {
        self._user_filter = filter.to_string();
        self
    }
}

impl AuthPolicy for LdapAuthPolicy {
    fn authenticate(&self, _request: &AuthRequest) -> AuthResult<AuthContext> {
        // 从请求中提取用户名和密码
        // 这里简化处理，实际应该从Authorization header或其他地方获取
        
        // 模拟LDAP认证
        let user_id = "ldap_user_456".to_string();
        let mut context = AuthContext::new(user_id);
        context.username = Some("ldap_user".to_string());
        context.roles = vec!["ldap_user".to_string(), "employee".to_string()];
        context.permissions = vec!["ldap.access".to_string()];

        Ok(context)
    }

    fn check_permission(&self, context: &AuthContext, required_policy: &str) -> AuthResult<bool> {
        if required_policy.is_empty() {
            return Ok(true);
        }

        if required_policy.starts_with("role:") {
            let role = &required_policy[5..];
            Ok(context.has_role(role))
        } else {
            Ok(true)
        }
    }
}

/// 数据库认证策略
#[async_trait]
pub trait DatabaseAuthRepository: Send + Sync {
    async fn validate_user(&self, username: &str, password: &str) -> Option<AuthContext>;
    async fn get_user_permissions(&self, user_id: &str) -> Vec<String>;
}

pub struct DatabaseAuthPolicy {
    #[allow(dead_code)]
    repository: Box<dyn DatabaseAuthRepository>,
}

impl DatabaseAuthPolicy {
    pub fn new(repository: Box<dyn DatabaseAuthRepository>) -> Self {
        Self { repository }
    }
}

impl AuthPolicy for DatabaseAuthPolicy {
    fn authenticate(&self, _request: &AuthRequest) -> AuthResult<AuthContext> {
        // 这里需要异步，但Auth trait目前是同步的
        // 在实际实现中，需要修改Auth trait为异步或使用其他方法
        // 暂时返回模拟数据
        
        let user_id = "db_user_789".to_string();
        let mut context = AuthContext::new(user_id);
        context.username = Some("db_user".to_string());
        context.roles = vec!["db_user".to_string()];
        context.permissions = vec!["db.access".to_string()];

        Ok(context)
    }

    fn check_permission(&self, context: &AuthContext, required_policy: &str) -> AuthResult<bool> {
        if required_policy.is_empty() {
            return Ok(true);
        }

        if required_policy.starts_with("permission:") {
            let permission = &required_policy[11..];
            Ok(context.has_permission(permission))
        } else {
            Ok(true)
        }
    }
}

/// 组合认证策略
pub struct CompositeAuthPolicy {
    policies: Vec<Box<dyn AuthPolicy>>,
    require_all: bool, // true: 需要所有策略都通过, false: 只需要一个策略通过
}

impl CompositeAuthPolicy {
    pub fn new(policies: Vec<Box<dyn AuthPolicy>>) -> Self {
        Self {
            policies,
            require_all: false,
        }
    }

    pub fn require_all(mut self) -> Self {
        self.require_all = true;
        self
    }

    pub fn require_any(mut self) -> Self {
        self.require_all = false;
        self
    }
}

impl AuthPolicy for CompositeAuthPolicy {
    fn authenticate(&self, request: &AuthRequest) -> AuthResult<AuthContext> {
        if self.policies.is_empty() {
            return Err(AuthError::InternalError("No authentication policies configured".to_string()));
        }

        let mut last_error = None;

        for policy in &self.policies {
            match policy.authenticate(request) {
                Ok(context) => {
                    if !self.require_all {
                        return Ok(context);
                    }
                }
                Err(e) => {
                    last_error = Some(e);
                    if self.require_all {
                        return Err(last_error.unwrap());
                    }
                }
            }
        }

        if self.require_all {
            // 如果需要所有策略都通过，返回最后一个成功的结果
            // 这里简化处理
            Ok(AuthContext::new("composite_user".to_string()))
        } else {
            Err(last_error.unwrap_or(AuthError::InvalidToken("All authentication methods failed".to_string())))
        }
    }

    fn check_permission(&self, context: &AuthContext, required_policy: &str) -> AuthResult<bool> {
        if self.policies.is_empty() {
            return Ok(true);
        }

        for policy in &self.policies {
            match policy.check_permission(context, required_policy) {
                Ok(true) => {
                    if !self.require_all {
                        return Ok(true);
                    }
                }
                Ok(false) => {
                    if self.require_all {
                        return Ok(false);
                    }
                }
                Err(_) => {
                    if self.require_all {
                        return Err(AuthError::AuthenticationFailed("Permission check failed".to_string()));
                    }
                }
            }
        }

        Ok(self.require_all)
    }
}